Sedimentation of chiral particles in viscous media

Sedimentation of particles is a classical problem of fluid mechanics. While it is well understood that the particle shape uniquely determines its dynamics, the precise trajectory and orientational dynamics are only known for a limited set of particle shapes. Here, we study theoretically sedimentation of chiral particles, focussing on rigid helical filaments and Moebius-strip ribbons. We combine the resistive-force theory, slender-ribbon theory, and numerical simulations to predict the details of particle trajectories. We demonstrate that the chirality of the particle leads to the chirality of its trajectory and discuss the physical origin of this phenomenon.